Server-sent events in http/af

sse.re

let set_interval = (s, f, destroy) => {
  let rec set_interval_loop = (s, f, n) => {
    let timeout =
      Lwt_timeout.create(s, () =>
        if (n > 0) {
          f();
          set_interval_loop(s, f, n - 1);
        } else {
          destroy();
        }
      );

    Lwt_timeout.start(timeout);
  };

  set_interval_loop(s, f, 5);
};
let response =
  Response.create(
    `OK,
    ~headers=
      Headers.of_list([
        ("Connection", "close"),
        ("Content-Type", "text/event-stream"),
      ]),
  );
let request_body = Reqd.request_body(reqd);
let response_body = Reqd.respond_with_streaming(reqd, response);
let rec on_read = (_request_data, ~off as _, ~len as _) =>
  Body.flush(response_body, () =>
    Body.schedule_read(request_body, ~on_eof, ~on_read)
  )
and on_eof = () =>
  set_interval(
    2,
    () => {
      let _ = Body.write_string(response_body, "data: some data\n\n");
      Body.flush(response_body, () => ());
    },
    () => {
      let _ = Body.write_string(response_body, "event: end\ndata: 1\n\n");
      Body.flush(response_body, () => Body.close_writer(response_body));
    },
  );
Body.flush(response_body, () => ());
Body.schedule_read(~on_read, ~on_eof, request_body);
Lwt.return_unit;